"According to the Wellcome Trust, the rise of the term mental health was largely due to the efforts of early 20th-century social reformers, who wanted to reduce the stigma attached to people who had been deemed mentally unwell. Whereas mental illness set up a verbal division between the healthy and the sick, the term mental health implied more of a continuum, a state that could improve or degrade in anyone over time.
If mental health is one of the newest tools that modern English has for describing the condition of the mind, then madness is one of the oldest."
For the full article, click here: http://www.theatlantic.com/health/archive/2015/10/mental-health-words/412630/